Starter quiz
- The exterior angles of any polygon __________ sum to 360°.
- always ✓
- sometimes
- never
-
- The interior angles of any polygon __________ sum to 360°.
- always
- sometimes ✓
- never
-
- An interior angle and its adjacent exterior angle __________ sum to 360°.
- always
- sometimes
- never ✓
-
- A regular polygon has exterior angles of size 24°. The polygon has ______ sides.
- '15' ✓
- The size of each exterior angle of a regular octagon is ______°.
- '45' ✓
- The regular polygon that has interior angles that are equal to its exterior angles is a ______.
- 'square' ✓
Exit quiz
Match each description to the correct statement.- unsimplified expression for angle sum⇔5 + 46 + 74 ✓
- simplified expression for angle sum⇔5 + 120 ✓
- equation for angle sum⇔5 + 120 = 180 ✓
- solution for⇔= 12 ✓
- angles in triangle⇔46°, 60°, 74° ✓
Find the value of .- 10
- 11.5
- 13 ✓
- 15
-
Find the value of .- 14 ✓
- 23
- 28
- 32
-
Find the value of . Give your answer correct to 3 significant figures.- 10.3
- 15.4
- 16.8 ✓
- 18.2
-
The value of is ______.- '147' ✓
Find an equation for in terms of .-
-
- ✓
-
-
-
Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Missing angles can be found in polygons using knowledge of exterior and interior angles.
- A missing angle can be represented with an unknown.
- Algebraic statements can be written about the missing angles in polygons.
Common misconception
Alternate angles are always equal to each other.
Alternate angles are equal when a transversal intersects parallel lines. If the transversal intersects a pair of lines that are not parallel then the alternate angles will not be equal.
Keywords
Interior angle - An interior angle is an angle formed inside a polygon by two of its edges.
Exterior angle - An exterior angle is an angle on the outside of a polygon between an extension of an edge and the adjacent edge.
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